Adjustable eccentric for sewing machines



Jan. 28, 1936. J. H. STEARNS 2,029,278

' ADJUSTABLE ECCENTRIC FOR SEWI-NGMACHINES Filed July 17, 19:54 3Sheets-Sheet 1 mac/who'd Jan/be fl dearnd I Jan. 28, 1936.

J. H. STEARNS ADJUSTABLE ECCENTRIC FOR; SEWING MACHINES Filed luly 17,1934 s Sheets-Sheet 2 H mm W m m w d A n 7 51 Jan. 28, 1936. J. H.STEARNS I ADJUSTABLE ECCENTRIC FOR SEWING MACHINES Filed July 17, 1934 sSheets-Sheet 5 Jake H s teamnd Guam;

Patented. Jan. 28, 1936 UNITED STATES PATENT OFFICE ADJUSTABLE EooEN'rmcroa SEWING MACHINES Application July 17, 1934, Serial No. 735,612

8 Claims.

This invention relates to improvements in ad- .iustable eccentrics foruse in connection with sewing machines and is herein described as asewing machine feed-actuating eccentric, al-

5 though adapted to other uses in connection with sewing machines.

The primary object of the invention is to provide an actuating eccentricforsewing machines which is conveniently adjustable as to eccentricity 1and definitely maintains any one of a plurality of set positions ofeccentricity at high speeds of operation and under heavy loadconditions.

More specifically, the present invention aims to improve the type ofadjustable feed-eccentric dis- 15 closed in the U. S. Patent to C. H.Willcox et al.,

No. 572,041, November 24, 1896.

With the above and other more specific objects in view, the inventioncomprises the devices, combinations and arrangements of partshereinafter described in connection with the accompanying drawings, fromwhich the several features of the invention and the advantages attainedthereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 represents a vertical sectionlongitudinally of the sewing machine. Fig. 2 represents a transversesection of the machine through the arm-standard thereof andsubstantially on the line 2-2 of Fig. 30 1. Fig. 3 is an enlarged detailview of one form of the improved feed-adjusting device from the sameside as shown in Fig. 2, but with the parts relatively adjusted into adifferent position thereof. Fig. 4 represents a sectional view of the 35feed-adjusting device substantially on the line 4-4 of Fig. 3. Fig. 5 isa face view of the feedeccentric flange from the side thereof oppositeto the eccentric. Fig. 6 is a similar view of the feed-adjusting diskfrom the eccentric-flange side 40 thereof. Fig. 7 represents a detailsectional view ofthe feed-adjusting device substantially on the line'l-Lof Fig. 3. Fig. 8 represents a longitudinal section of amodiflcation of the feed-adjusting device. Fig. 9 represents across-section 45 of the modification substantially on the line 9-9 ofFig. 8. Figs. 10 to 13, inclusive, represent perspective views of thecomponent parts of the modified feed-adjusting device illustrated inFig. 8.

Referring to the drawings, the present improvements have been embodiedin a sewing machine including a frame comprising a bed-plate I, from oneend ofwhich rises a hollow standard 2 of a tubular bracket-arm 3overhanging the bed-plate 56 and terminating at its free end in a head4.

Disposed within and extending longitudinally of the bracket-arm 3 is arotary main or needlereciprocating shaft 5, carrying at its outer end acombination balance-wheel and driving-pulley 6. Adjacent to thebalance-wheel, the shaft 5 is 5 journaled in a ball-bearing I, theopposite end of the shaft being journaled in a bearing bushing 8 withinthe bracket-arm 3. The shaft 5 carries a crank-disk 9 connected by alink III to the upper end of .a needle-bar ll, journaled for ver- 10tical reciprocation in an elongated bushing l2 suitably fixed in thebracket-arm head 4. At its lower end, the needle-bar II carries a needlel3. Also journaled for vertical movement in the bracket-arm head is theusual presser-bar [4, to the lower end of which is secured apresser-foot l5.

Suitably secured upon the main shaft 5 for rotation therewith is aperipherally grooved pulley it connected, by a clip-belt H, with apulley l8 of one half the size of pulley It. The pulley I8 is carried byone end of a loop-taker shaft 19 disposed below the bed-plate l and inparallelism with the main shaft 5. Adjacent to the pulley l8, theloop-taker shaft I9 is journaled in a ballbearing 20, the opposite endof said shaft being journaled in a bearing bushing 2| and-carrying aloop-taker 22 adapted to cooperate with the needle IS in the formationof lock-stitches.

The work to be stitched is intermittently advanced by a feedingmechanism of the lower fourmotion type and comprising a feed-dog 23carried by a feed-bar 24. One end of the feed-bar is operativelyconnected to a crank-arm upon one end of a feed-lift rock-shaft 25journaled below and extending longitudinally of the bed-plate I.Adjacent to its opposite end, the rock-shaft 25 carries a crank-arm 26pivotally connected to the lower end of a pitman 21 of which theopposite end has a strap 28 embracing a suitable feed-lift eccentric 29carried by the main shaft 5.

The feed-bar 24 is also pivotally connected to a feed-rocker 30 carriedby a feed-advance rockshaft 3| journaled below and extendinglongitudinally of the bed-plate l. Clamped upon the rock-shaft 3| is acrank-arm 32 pivotally connected to the lower end of a pitman 33, ofwhich the upper end has a strap 34 embracing an eccentric 35. It is thesupporting'and adjusting mechanism for this eccentric which constitutesthe present invention, although, as hereinbefore 60 indicated, aneccentric supported and adjustable in like manner may be employed in asewing machine for actuating an element other than the feed-dog.

According to the construction illustrated in tric 35 surrounds the mainshaft 5 and has an enlarged circular shaft-aperture 35, althoughobviously this aperture may be ovate if preferred. The eccentric 35' hasa peripherally indexed end flange 31 comprising, in effect, a diskrotatable with the eccentric. The flange-disk '31 is provided with apair of diametrically alined and elongated slcts 38 through which passstud-screws 39 threaded into apertures 89 provided in the beltpulley 6,whereby'the eccentric 35 is secured for rotation with the main shaft 5,but is adjustable radially of the shaft as to eccentricity.

Disposed upon the main-shaft 5, between the flange-disk 31 and thepulley i5, is an adjustingcam or disk 4|, provided with arcuate slots 42at opposite sides and concentric with the main-shaft 5, said slots 42receiving and providing clearance for the stud-screws 39 upon relativerotation of the eccentric 35 and the adjusting cam 91. Friction washers43, interposed between the heads of the stud-screws 39 and theflange-disk 31 serve to yieldingly maintain the eccentric and camagainst any substantial movement endwise of the main-shaft 5. Projectingfrom the adjustingcam side of the flange-disk 31 is a pin 95 carrying acam-roller 95 entering a cam-groove d6 prcvided in the adjacent sideface of the adjusting cam, whereby the eccentric and cam are soconnected that relative rotation thereof effects adjustment of theeccentric 35 as to eccentricity.

The adjusting cam All is peripherally provided with a stop-notch 41adapted to be entered by the nose 39 of a manually operable latch-memberin the form of a bell-crank lever 49, 59, fulcrumed upon a pivot-screw5| and between spaced ears 52 provided upon the front wall-of the armstandard 2 to receive the pivot-screw. The latch-member arm 49 which hasthe nose 48 extends into the arm-standard through a suitable slot 53 inthe arm-standard front wall, while the arm of said latch-member isflattened to provide a thumbp'iece at the outer side of the armstandard. A spring 54 acts to yieldingly hold the latch-member retractedfrom engagement with the adjusting cam. When the nose 48 of thelatch-member is caused to enter the adjusting-cam notch 41, saidadjusting cam is restrained against rotation with the shaft 5 and,consequently, by now turning said shaft 5, the eccentric 35 will beadjusted as to eccentricity.

In prior constructions, reliance has been placed upon the frictionwashers 93 to maintain the eccentric 95 in adjusted position duringthe-operation of the machine, 1. e., to maintain unison rotation of theadjusting camfll and eccentric 95. However, at higher speeds ofoperation and heavy load conditions, a slippage occurs between theeccentric and cam, thereby dislodging the eccentric from set position.This liability to slippage may be overcome up to a'certain speed ofoperation of the machine by tightly clamping the cam M and eccentric 35together, by means of'the stud-screws 39. However, when so tightlyclamped as to re-- duce liability of slippage between the cam andeccentric during the operation of the machine, it

becomesextremely difjficult to effect adjustment of the eccentric byturning the main-shaft 5, in

a position of the latch-member 89, 50 wherein the cam isrestrainedagainst rotation. I According to the present invention, the eccentric 35and adjusting cam 4| are normally posietively locked together for unison,rotation during the operation of the machine, the locking means beingreadily releasable and preferably simulta- Figs. 1 to 7, inclusive, ofthe drawings, the eccenneously with theanchoring of the adjusting camagainst rotation. To this end, the adjusting cam 41 is provided with aradial aperture 55 opening ed to be engaged by the detent-head 51, saidhead being shaped to fit the teeth of the rack 59 in poe sitionscorresponding to the markings, or index,

upon the periphery of the flange-disk 31. A spring 60 housed in theaperture 55 acts to normally seat the detent in locking engagement withthe rack 59. As the detent head 51 extends into the stopnotch 41 of thecam, said detent is also disposed in the path of movement of thelatch-member nose 48 into cam-anchoring position."

It will therefore be understood that, while the eccentric and adjustingcam are positively locked against relative slippage during the normaloperation of the machine, the latch-member not only serves as means toanchor the cam but simultaneously therewith acts to unseatjthe detent56, 51 from the toothed rack 59, so that the main-shaft may be easilyturned to eifect'adjustment of the eccentric. It will alsobe'understoodthat the provision of the positive locking means described eliminatesany necessityfor tightly clamping the cam and eccentric together bymeans of thestudscrews 39, it being merely necessary tb maintaincooperative relationship between said elements.

In the modification illustrated in Figs. 8.to 13 inclusive of theydrawings, novel means are provided for securing an eccentric to theactuating diametrically grooving a side face of .a collar 61- secured byset-screws 58 upon the shaft 5, said collar 61 together with the collar64 also serving to maintain cooperative relationship between theeccentric 6i and cam 63 as to relative movement endwise of the shaft.

As in the construction herein first described, the eccentric-flange 62carries a cam-roller 59 entering a cam-groove 10 in the adjacent sideface of the adjusting cam 63. The adjusting cam 63, likewise, isprovided with a spring-pressed detent 11 extending into a stop-notch 1'2in the periphery of the adjusting cam, said detent normally engaging anarcuate rack 13 in the recessed side face of the eccentric-fiange62 topositively lock the adjusting cam and eccentric for unison rotationduring the operation of themachine.

Having thus set forth the nature of the invention, what I claim hereinis 1. In a sewing machine, a rotary shaft, an actuating eccentric havingan arcuate rack, means for securing said eccentric for rotation withsaid shaft and'providing for right line adjustment of the eccentriccrosswise of the shaft, an adjusting cam rotatablymounted upon saidshaft, a connection between said cam and eccentric whereby relativerotation of the cam and eccentric efiects adjustment of the eccentricityof the eccentric, a

the eccentric crosswise of the shaft, an adjusting cam loosely mountedupon said shaft and peripherally provided with a stop-notch, aconnection between said cam and eccentric whereby relative rotation ofthe cam and eccentric effects adjustment of the eccentricity of theeccentric, a springpressed detent carried by said cam for engagementwith said rack, said detent in its rack-engaging position extending intosaid stop-notch of the cam, and a manually operable latch-member adaptedto enter the cam stop-notch and shiftably engage said detent, to therebyrestrain said cam against rotation and to release said detent.

3. In a feeding mechanism for sewing machines, a rotary shaft, anadjusting cam rotatably disposed upon said shaft and having a peripheralstop notch, a feed actuating eccentric provided with an arcuate rack,said eccentric and rack being disposed at the same side of saidadjusting cam, means for securing said eccentric for rotation with saidshaft and providing for adjustment of the eccentricity of the eccentric,a connection between said cam and eccentric for effecting adjustment ofthe eccentric upon relative rotation of the cam and eccentric, aspringpressed detent carried by said cam in engagement with said rack toinsure unison rotation of the eccentric and cam, and a manually operablelatch member adapted. to enter the stop notch of said cam and shiftablyengage said detent to release the detent and to restrain said camagainst rotation.

d. In a feeding mechanism for sewing machines, a rotary shaft, afeed-actuating eccentric disposed upon said shaft for adjustment as toeccentricity, 'said eccentric having an end flange provided with anarcuate toothed rack, an adjusting cam rotatably disposed upon saidshaft adjacent to the eccentric flange, said cam having a radialaperture terminating in a peripheral stopnotch, a spring-pressed detenthaving a shank slidably disposed in said radial aperture of the cam andhaving a transverse head positioned in said stop-notch for normalengagement with the teeth of said rack, a connection between said camand eccentric for effecting adjustment of the eccentric upon relativerotation of the cam and eccentric, means for maintaining said cam andeccentric in cooperativerelation, and a latch-member adapted to bemanually operated to enter the stop-notch of said cam and shiftablyengage said detent to release the detent and to restrain said camagainst rotation.

5. In a sewing machine, a rotary shaft, an ec- 1 centric disposed uponsaid shaft for radial adjustment, an adjusting cam rotatably mountedupon said shaft adjacent one end of said eccentric, a connection betweensaidcam and eccentric whereby relative rotation thereof effectsadjustment of the eccentric radially of the shaft, and opposed collarssecured upon said shaft for restraining said cam and eccentric againstmovement endwise of said shaft, said eccentric being adjustably keyed toone of said collars to confine Y the eccentric to rotation with saidshaft and toprovide for radial adjustment of the eccentric.

6. In a sewing machine, a rotary shaft, an eccentric disposed upon saidshaft for radial adjustment, an adjusting cam rotatably mounted uponsaid shaft adjacent one end of said eccentric, a connection between saidcam and eccentric whereby relative rotation thereof effects adjustmentof the eccentric radially of the shaft, a collar secured upon said shaftadjacent the end of said eccentric opposite to the cam end thereof, saidcollar having a tongue-and-groove connection with said eccentric toconfine the eccentric to rotation with said shaft, means maintainingsaid cam and eccentric in cooperative relation, and means normallyeffective during the operation of the machine to effect rotation of saidcam in unison with said eccentric.

7. In a sewing machine, a rotary shaft, an actuating eccentric, meansfor securing said eccentric for rotation with said shaft and providingfor adjustment of the eccentricity of the eccentric, an adjusting camloosely mounted upon said shaft and operatively connected with saideccentric to efiect adjustment of the eccentricity of the eccentric uponrelative rotation of the cam and eccentric, interengaging locking meansprovided upon said eccentric and cam effective to positively secure saidcam for rotation with said eccentric, and manually operable means foreffecting release of said locking means.

8. In a sewing machine, a rotary shaft, an actuating eccentric providedwith an arcuate rack having its center of curvature non-coincident withthe center of curvature of the peripheral face of said eccentric, meansfor securing said eccentric for rotation with said shaft and providingfor adjustment of the eccentricity of the eccentric, an adjusting camrotatably mounted upon said shaft, a connection between said cam andeccentric whereby relative rotation of the cam and eccentric effectsadjustment of the eccentricity of the eccentric, a spring-pressed detentcarried by said cam for engagement with said rack, and manually operablemeans for effecting release of said detent.

JAKE H. S'I'EARNS.

